He will hold on and win. Last year he was the best climber in the last week next to Contador and Landa. Contador didn't start this time and Landa has left the Giro earlier because he was ill. Besides, he won a lot of time again yesterday and now has a 3 minute advantage on the number two. Unless he becomes ill himself or blows up somehow, he will hold on and may even improve his lead on friday and saturday.
Ok, there was another option besides illness or blowing himself up. Yesterday Kruiswijk fell in a downhill section and hit a snow/ice wall. He finished the stage despite a fractured rib and foot injury. Chaves took over the lead but today Nibali took it back. With just the flat ride to Milan left it looks like Nibali will win, Chaves in second and Valverde in third. Such a shame, Kruiswijk was the strongest rider this Giro and would've won easily had he not made that mistake. Then again staying on your bike is also a part of cycling.